Essentials of Nutrition for Sports

It did not change average power or VO2, though time to
completion of a 12.5-kilometer time trial was improved in one study.

It is premature to say whether tribulus works. If it does, it

probably has anabolic-type side effects.

Tribulus supplements have been found to be contaminated with

anabolic steroids.

Avoid.

Tyrosine

Not banned. See discussion under protein, at

hletic considerations, on page

63

.

Not recommended.

Vanadyl Sulfate

Not banned. Vanadyl sulfate is purported to mimic the activity of insulin, but

there have been no performance studies in humans.

Not recommended.

Vasodilators

Not banned. Prescription. Nitroglycerin, for example, is reportedly used by some athletes

near the end of a competition, not before or during. Studies are lacking. There are serious side effects.

Avoid.

Vitamins

Not banned. If you eat a balanced diet, the usual advice is that you do not

need any extra vitamins. A general multivitamin, costing about a dime a day, may be used as insuran

ce. Anything additional is a waste

of money. Side effects from high doses do exist. Some vitamins taken in excess worsen performance.

“Vitamin B15”—pangamic acid—is an example of a substance

sold to athletes with no recognized status in the scientific community and little to recommend it beyond hope and a placebo effect.

Read more about the ergogenic and ergolytic effects of vitamins

on page

126

.

Consider only in doses up to the RDA.

Water

The most important “ergogenic” aid, not banned, perfectly legal.

Read more about hydration on page

27

.^

Endorsed.

Nutrition for Sports, Essentials of 123